The present invention relates to a flow control valve for controlling fluid flow to and from a fluid motor.
Conventional pressure-compensated flow conrol valves, such as described in U.S. Pat. No. 3,587,630, have spool-type directional control valves which provide metering of return fluid flow downstream from the load check valves. In some instances, such as under the influence of an overrunning load, this metering downstream from the load check valve reduces the pressure drop across the return fluid load check valve so that the pressure immediately downstream of the return load check valve is high enough to cause the pilot-operated return valve elements to permit closing of the return load check valve. Such a valve will then enter an undesirable cycling or chattering mode of operation. Furthermore, such valves do not provide a convenient means for independently varying the return flow metering in both directions. Furthermore, when the number of these functions reaches a certain number, it becomes practical to control the functions by means of electrohydraulic valves.